The present invention relates to a suspension control apparatus for a vehicle, which is mounted on, for example, a vehicle such as a four-wheel automobile so as to be suitably used to damp a vibration of the vehicle. Also, the present invention relates to a control apparatus for a damping-force adjustable shock absorber, which is mounted on, for example, a vehicle such as a four-wheel automobile so as to be suitably used to damp a vibration of the vehicle.
In general, on a vehicle such as an automobile, a damping-force adjustable shock absorber is provided between a vehicle body and each axle. In addition, a control apparatus for variably controlling damping-force characteristics obtained by the shock absorber according to road-surface conditions or the like is mounted on the vehicle (for example, see JP 61-135810 A and JP 2008-247380 A).
The above-mentioned type of control apparatus for the damping-force adjustable shock absorber in the related art increases a damping force based on the skyhook control theory when the vehicle runs on, for example, an “undulating road” on which the vehicle body (sprung) side is moved widely at a low frequency. In this manner, vibration damping is performed for the vehicle body side. Even under the conditions under which an unsprung vibration is generated when the vehicle runs on, for example, a road in bad conditions or a road surface having protrusions that might affect the vehicle, the damping force is similarly increased to damp the vibration on the unsprung (wheel) side.
On the other hand, if the damping-force characteristics of the shock absorber are controlled to be harder to increase the generated damping force, abnormal noise which is so-called “clattering noise” is sometimes generated.
Therefore, in the related art, for increasing or reducing the damping force of the shock absorber, control is performed so that the damping force is gradually changed or an initial increase rate of a current applied to the shock absorber is reduced, so that the generation of the abnormal noise called “clattering noise” can be suppressed.
However, the control apparatus for the damping-force adjustable shock absorber described above according to the related art has a configuration for merely suppressing a rapid change in damping force so as to suppress the generation of the abnormal noise called “clattering noise”. Accordingly, the above-mentioned control apparatus for the damping-force adjustable shock absorber has a problem in that the generation of the “clattering noise” cannot always be fully suppressed.